Objective: Calabash chalk (Nzu) is a geophagic material, consumed by many pregnant women and breastfeeding mothers as remedy for morning sickness in most African countries. The present study aims to evaluate the impact of Calabash chalk consumption in pregnant Wistar rats. Materials and Methods: Median lethal dose of Calabash chalk was initially determined in Wistar rats to be >5000 mg/kg po using Lorke's method. Thereafter, 24 pregnant Wistar rats were divided randomly into 3 groups (n = 8) and orally administered 0, 400, or 800 mg/kg of Calabash chalk from gestation day 0 to 20. Maternal body weights were monitored during sample administration. Fetuses were delivered under anesthesia by cesarean section and pregnancy outcome was assessed. Results: Calabash chalk exposure inhibited maternal weight gain. Uterine implantations were absent in 85% of Calabash chalk exposed rats, and the number of implantation sites were decreased (P = 0.0262) in the rest, compared to control. Uterine weight and the number of fetuses formed in uterine horns of Calabash chalk exposed pregnant rats were decreased (P = 0.0204) when compared with control. In addition, there was resorption of pregnancy, abortion (58%), and stillbirth (5%) in Calabash chalk exposed rats, and fetuses delivered were sluggish and pale. Most of these effects observed were dose-dependent. Conclusion: The results suggest that Calabash chalk has a negative relationship with maternal health and pregnancy outcome.